Interdental stimulator

ABSTRACT

An improved interdental stimulator device designed for use in cleaning and polishing tooth surfaces and for safe gingival stimulation takes the form of a unitary body molded of synthetic plastic material. The unitary body is of generally elongated shape and has a first working end which tapers substantially to a point and has a cross section generally taking the form of an isosceles triangle, the base and sides of which may have a slight outward curvature. Preferably, the body is impregnated with up to about 20% by weight of a dental abrasive material, especially a dental abrasive material comprising zirconium silicate. The body may have at its other end a flat-sided projecting member as a second working end.

United States Patent Muhler 1 Oct. 17, 1972 [54] INTERDENTAL STIMULATOR 3,330,732 7/1967 Muhler ..l32/89 UX Inventor: C Muhler Indianapolis, d Assigneei Planck p y 'g Mich- Primary Examiner-Lawrence W. Trapp Attorney-Ronald L. Engel, Daniel W. Vittum, Jr. and

7 [22] Jan l9 1 Gomer W. Walters [21] Appl. No.: 105,691

Related U.S. Application Data [57] ABSTRACT An improved interdental stimulator device designed [63] fgg f z for use in cleaning and polishing tooth surfaces and a an one for safe gingival stimulation takes the form of a unitary body molded of synthetic plastic material. The uni- [gi] tary body is of generally elongated shape and has a d 32/89 first working end which tapers substantially to a point 0 32/58 and has a cross section generally taking the form of an isosceles triangle, the base and sides of which may 56 R f Cited have a slight outward curvature. Preferably, the body I 1 e i is impregnated with up to about 20% by weight of a UNITED STATES PATENTS dental abrasive material, especially a dental abrasive 7 material comprising zirconium silicate. The body may Qf have at its other end a flat-sided projecting member as iseman asecond workin emi 1,138,479 5/1915 Hough ..132/s9 x g 2,507,299 5/1950 DAlelio ..l32/89 UK 17 Claims, 8 Drawing Figures PATENTEDHBHYIBYZ 3.698.388

6 JOSEPH a MUH w INTERDENTAL STIMULATOR This application is a continuation of abandoned application Ser. No. 798,883 filed Feb. 13, 1969.

SUMMARY OF THE INVENTION 1. Field of the Invention The present invention relates to the dental arts and more particularly to an interdental stimulator device especially designed to clean and polish interproximal areas without abrasion and to accomplish stimulation of the gingival tissue.

2. Description of the Prior Art The use of wooden'toothpicks andthe like as interdental stimulators has, of course, long been known. However, a number of disadvantages attend the use of such wooden articles in the oral cavity. Because they are made of wood, there is the ever present danger of the splinters injuring the gingival tissue. Indeed, it has been found that such wooden devices, if not used properly, may cause pronounced inflammation of the epithelium with ulceration, myositis and bacterial inversion of the submucosa, and increased osteoclastic activity in the supporting hard tissues leading to marked resorption of the alveolar crest after as little as three weeks of use. Due to their porous nature, wooden devices are unsanitary and can be sources of contamination. Thus, because of their design and the material of which they are made, such stimulators are capable of substantial harm to the teeth and gums.

Furthermore, toothpicks are merely passive devices and have no active hygienic or therapeutic function when used in the interproximal regions of the oral cavity. The latter disadvantage of prior art devices is particularly significant because the interproximal areas, which cannot be readily reached with ordinary toothbrushes, are often the site of carious lesions and because the interproximal gingiva require mild stimulation.

SUMMARY OF THE INVENTION The foregoing disadvantages of prior art stimulators are overcome by the present invention which provides an interdental stimulator device for use in cleaning and polishing tooth surfaces,.especially the interproximal surfaces, and for safe gingival stimulation purposes. This device comprises a unitary body molded of synthetic plastic material. The unitary body is of generally elongated shape and has a first working end that tapers to a point, the first working end having a cross section generally taking the form of an isosceles triangle, the base and sides of which may have a slight outward curvature. The plastic body is preferably impregnated with up to about percent by weight of a dental abrasive material, especially a dental abrasive material comprising zirconium silicate (ZrSiO The body may have at its other end a thin, flat-sided projecting member as a second working end.

The device advantageously is provided with a second working end taking the form of a thin projecting flange of substantially uniform top to bottom dimension.

Accordingly, a primary object of the present invention is to provide an interdental stimulator device that avoids the sanitation and tissue damage problems posed by prior art wooden devices.

A further object is to provide an interdental stimulator device of the character described fabricated from synthetic plastic material.

Yet another object is to provide an interdental stimulator device of the character described fabricated from synthetic plastic material containing a dental abrasive material that is capable of performing hygienic and therapeutic functions when used in the oral cavity.

DESCRIPTION OF THE DRAWINGS FIG. 7 is a partially schematic view of plastic molding equipment capable of manufacturing the device shown in FIG. 1;and

FIG. 8 is a partially schematic view showing the device of FIG. I properly placed in the interproximal areas between two teeth.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an interdental stimulator device 10 produced in accordance with the present invention which takes the form of an elongated member tapering to a point at one end. The device10 has a first working end 20 having a cross section that, as best shown in FIGS. 5 and 6, generally takes the form of an isosceles triangle having a pair of flat sides l2, 14 meeting at a narrow blunted knife edge 16. The center portion of device 10 has a generally rectangular cross section (see FIG. 6). However, the working end 20 is provided so that the elongated member is reduced to a point 22 at one end.

The device has a second working end 24 at its opposite end. Working end 24 takes the form of a thin, flexible projecting member of substantially uniform thickness (see FIG. 4).

The interdental stimulator 10 is preferably molded I from synthetic plastic material in a conventional injection molding apparatus 28 shown schematically in FIG. 7. Apparatus 28 includes an upper mold part 30 and a lower mold part 32 mounted by means (not shown) to permit mold parts 30, 32 to be moved from the open position shown in FIG. 7 to a closed position. A pair of mold cavities 34, 36 are respectively cut in molds 30, 32. Cavities 34, 36 each correspond to one-half of the interdental stimulator device 10, and, when apparatus 28 is closed cavities 34, 36 define a volume into which synthetic plastic material is forced via a passageway defined by a pair of slots 29, 31 provided in mold blocks 30, 32, respectively. Suitable gate means (not shown) for controlling the flow of synthetic plastic material are provided as are means (not shown) for supplying heated synthetic plastic material under pressure. Of course, other suitable plastic molding and fabricating techniques may be employed to produce stimulator 10. For example, a typical mold used for a commercial production run would comprise a relatively large number of individual cavities fed by a common plastic injection system.

Stimulator 10 may be made from any number of suitable plastic materials. Typical materials which may advantageously be employed include polyamides (such as nylon), flexible polystyrene, polyethylene,

polypropylene, and the like. Nylon is an especially preferred plastic for use in producing interdental stimulators in accordance with the present invention.

As previously noted, a special feature of the device of the present invention is that up to about 20 percent by weight of a dental abrasive material is incorporated in the plastic material. The abrasive material may be incorporated into the plastic from which the device is molded in any convenient fashion. For example, the abrasive material may be physically mixed with the plastic material before it is pelletized, or, alternatively, plastic pellets and abrasive in suitable quantities may be admixed in a suitable grinder prior to introduction of the plastic into the injection molding apparatus. Sub-- stantially any such method may be employed so long as the molten plastic reaching the mold cavities 34, 36 contains up to about 20 percent by weight of the cleaning and polishing agent.

While up to about 20 percent by weight of the abrasive material may be used with satisfactory results, best results are achieved with about 5-15 percent and preferably about percent abrasive by weight.

Acceptable results can be obtained with any of the large number of dental abrasive materials such as zirconium silicate (ZrSiO talc [Mg Si O '(Ol-l) calcium pyrophosphate (Ca P O calcium hydrogen phosphate dihydrate/anhydrous calcium hydrogen phosphate (CaHPO 'ZH O/CaHPO insoluble sodium metaphosphate [(NaPOQ calcium carbonate (CaCO alumina (Al- 0 and others. Zirconium silicate is the especially preferred abrasive for use in practicing the present invention, and mixtures comprising zirconium silicate and one or more of the foregoing other dental cleaning and polishing agents may advantageously be employed. There is no practical maximum level for the zirconium silicate since as pointed out elsewhere zirconium silicate per se is a dental cleaning and polishing agent in its own right.

However, especially good results are achieved where the dental abrasive is a particular form of zirconium silicate. The preferred zirconium silicate comprises a mixture of relatively large size ZrSiO, particles (i.e., roughly in the range of 10-75 microns particle size) and relatively small ZrSiO, particles (i.e., less than about l0 microns and preferably less than about 3 microns particle size).

The large size ZrSiO, particles are preferably distributed over three defined levels, namely, a first level of up to about 20 microns particle size; a second level of from about 20 microns up to about 50 microns particle size; and a third level of from about 50 up to about 75 microns particle size. Preferably, the said levels are combined in a composition having percentage ratio ranges of about 10-50 percent in the first level; 5-25 percent in the third level; and the balance in the second level. As noted, substantially all of the small ZrSiO, particles are less than about 3 microns particle size. The large ZrSiO, particles preferably predominate in the mixture on a weight basis (i.e., the mixture comprises at least about 50 percent large particles, by weight), with optimum results being achieved with a 9:1 large particle-small particle weight range.

The size of particles of dental abrasives can be expressed in a number of different ways, one of the most common of which is mean diameterf, i.e., the

arithmetical average of the diameters of particles in a representative sample. As used herein, the term particle size" refers to a mean diameter value.

Zirconium silicate is a well-known industrial abrasive which is used for the grinding and polishing of glass and ceramics. However, prior to the subject invention, this material had not been proposed for use as a cleaning and polishing material incorporated directly in a dental stimulator for frequent and direct application to the teeth. The extreme hardness and the abrasion characteristics exhibited by zirconium silicate (e.g., a hardness number of 7.5 on the Mohs scale for commercially available zirconium silicate, such as types used for grinding of glass) would suggest to one skilled in the art that zirconium silicate would seriously damage (i.e., abrade and scratch) tooth structure and would thus be unsuitable for use on the teeth. However, it has been ascertained that it may safely be employed under the conditions of the present invention.

The preparation of suitable particle size zirconium silicate can be accomplished by conventional techniques well known to the art. Basically, these techniques involve milling zirconium silicate ore (zircon), following by standard screen sieving (or air separation) to segregate the desired particle size. Various milling techniques may be utilized in order to obtain the desired surface configurations for the zirconium silicate particles. For example, particles may be prepared by ball and hammer milling techniques. Preferably, the cleaning and polishing agent of the present invention comprises a mixture of ball milled and hammer milled particles.

As iswell known to the art, hammer mills utilize a high speed rotary shaft having a plurality of hammers or beaters mounted thereon. The hammers may be T- shaped elements, bars, or rings fixed or pivoted to the shaft or to discs pivoted to the shaft. The shaft runs in a housing containing grinding plates or liners. The grinding action results from the impact between the material being milled and the moving hammers. When zircon ore is milled by an attrition technique such as hammer milling, relatively rough, jagged particles are produced. Particles having such jagged surface configuration function from a tooth cleaning standpoint in a relatively superior manner as compared to more smoothly configured particles.

Similarly, a ball mill comprises a cylindrical or conical shell rotating on a horizontal axis which is charged with a grinding medium such as balls of steel, flint, or porcelain. The grinding is accomplished by the tumbling action of the balls on the material to be ground. Particles of zirconium silicate treated in a ball mill of the character described have relatively smooth surface configurations and function better from the polishing standpoint than more jaggedly configured particles. Similar techniques can be employed with the other abrasives employed with the present invention.

FIG. 8 illustrates, in a schematic fashion, the stimulator device 10 of the present invention as used in the oral cavity. Device 10 is shown with its first working end so positioned in the interproximal area between a pair of teeth T, T'. The sides of working end 20 are adapted to contact the tooth surfaces, and the presence of the dental abrasive material imbedded in the plastic provides a superior cleaning and polishing vehicle adapted to clean and polish the dental enamel without abrasion. Because of the relative inaccessibility of the interproximal areasto conventional toothbrushes, use of the device of the present invention provides a substantial therapeutic aid in cleaning and polishing the teeth and therefore rendering the teeth less susceptible to dental caries and to the accumulation and re-accumulation of dental plaque, pellicle, and dental calculus (tartar).

Furthermore, the base 18 of stimulator as the device is moved in and out of the interproximal areas in a direction parallel to the gingival surface is adapted to gently contact and massage the gingival tissue G adjacent the gingival margin in the interproximal areas. Once again, this provides a source of therapeutic benefit not achievable with conventional toothbrushes or other appliances. Advantageously, the working end 20 is inserted and passed through an arc in orderto assure that the desired slight uniform gingival massage is accomplished. The surfaces leading up to knife edge 24 at the other working end may advantageously be employed to clean and polish other (i.e., labial, lingual, buccal, and occlusal) tooth surfaces. The stimulator is desirably maintained at an angle to the tooth surface, the end 24 being sufficiently flexible to permit contact to be maintained with the tooth surface, and the device is moved along the surface of the tooth in a direction away from the gingival margin. This operation is repeated until the desired level of cleaning and polishing have been achieved.

EXPERIMENTAL EVALUATIONS The superiority of the abrasive-containing stimulators of the present invention has been substantiated by the following experimental evaluations. A definitive laboratory cleaning test procedure has been used to evaluate the device of the present invention. This procedure (as set forth and described in Cooley et al U.S. Pat. No. 3,151,027) involved the use of polyester plastic blocks specifically designed for use in an electrical toothbrushing machine. The blocks are ground smooth, washed, dried, and a thin coating of black lacquer (previously observed to simulate dental pellicle) was carefully applied to the surface of the block. The blocks were then inserted in the toothbrushing machine and brushed with the stimulators for 100 double strokes with a pressure on the lacquer surface of 150 grams in the presence of 75 ml. of water. The amount of lacquer removed by the rubbing procedure was determined by a comparison'of preand post-treatment reflectance measurements. Cleaning values are given on a scale ranging from 0 to 6.5, a higher value indicating greater lacquer removal and hence a greater cleaning ability.

Enamel polishing values have also been obtained for the same materials in accordance with a so-called toothbrush polishing procedure. In accordance with this method, the linqual surfaces of freshly extracted maxillary anterior teeth are reduced with the aid of a diamond disc, and the teeth are mounted by means of a low melting alloy, such as Woods metal, on hexagonal jigs constructed so as to fit the movable state of a reflectometer. The exposed labial surface of each tooth is mounted in such a manner that the height of the contour is a suitable distance above the base of the jig.

Throughout the procedure, care is taken to ensure that the teeth do not become dry in order to prevent damage of the tooth tissues. The exposed enamel surface is then dulled by exposing it to 0.10 percent hydrochloric acid (pH 2.2) for 30 seconds. Any acid remaining on the tooth surface is neutralized by immediately transferring the tooth to a saturated sodium carbonate solution for 30 seconds. The tooth is then rinsed with water and blotted dry.

The maximum reflectance of the dulled tooth surface is determined by means of a reflectometer especially adapted to detect the changes in the degree of polish of the enamel surface. The reflectometer is constructed so that the enamel is exposed to a beam of polarized light, and the amount of light reflected from the enamel surface is determined by a photoelectric cell which in turn activates a galvanometer. The smoother the enamel surface, the smaller the amount of diffused and. absorbed light and, hence, the higher the galvanometer reading.

After the maximum reflectance of the dulled tooth is determined, the tooth is polished with a stimulator in an automatic toothbrushing machine in the presence of ml. of water utilizing double strokes and a tension of grams. After the tooth has been polished, the enamel surface is rinsed with water so as to remove any residual particles of the cleaning and polishing agent, and the reflectance of the enamel surface is again measured with the tooth located in exactly the same position as that used to obtain the dull reading. The absolute change in the amount of reflectance between the dulled and polished enamel surfaces is taken as a measure of the degree of polishing imparted by the prophylaxis treatment. I

Cleaning values and polishing scores are given in Table l for the preferred device of the present invention (i.e., a nylon stimulator comprising 10 percent by weight of a 9:1 weight mixture of large and small Zr- SiO particles). For comparative purposes, similar values obtained with a commercially available wooden stimulator are also given.

Thus, the preferred device of the present invention not only greatly enhances tooth cleaning, it also very substantially improves polishing, a remarkable result when it is realized that cleaning and polishing often are inconsistent objectives (i.e., an improvement in polishing often is obtained only with a concommitant reduction in cleaning, and vice versa).

Where abrasive materials other than the preferred ZrSiO are employed, the results do not appear to be as remarkable, but cleaning and/or polishing is improved in virtually every case.

From the foregoing it can beseen that the abrasivecontaining interdental stimulator of the present invention represents a substantial advance in the dental health arts. The use of this device permits one to clean and polish the interproximal tooth surfaces so as to remove and inhibit the reformation of interproximal plaque, pellicle, and calculus. Likewise, it provides a safe, sanitary method for mildly stimulating the gingival tissues.

I claim:

1. An interdental stimulator adapted for use in cleaning and polishing the teeth without undue abrasion and further adapted to safely stimulate gingival tissue, the said stimulator comprising a unitary body molded of a water insoluble plastic material, the said unitary body being of generally elongated shape and having first working end generally triangular in cross-section and tapering substantially to a point, the plastic material having permanently incorporated throughout a dental abrasive material.

2. A stimulator, as claimed in claim 1, wherein the cross-section of the first working end generally takes the form of an isosceles triangle.

3. A stimulator, as claimed in claim 1, wherein the surfaces of the first working end are curved outwardly slightly.

4. A stimulator, as claimed in claim 1, wherein a second working end is provided at the end of the unitary body opposite the first working end, the second working end taking the form of a thin, flexible, flatsided projecting member of substantially uniform thickness.

5. A stimulator, as claimed in claim 1, wherein the plastic is nylon.

6. A stimulator, as claimed in claim 1, wherein the plastic material has incorporated therein a dental abrasive material.

7. A stimulator, as claimed in claim 1, wherein the dental abrasive is present in the plastic material at a level of about -15 percent by weight.

8. A stimulator, as claimed in claim 1, wherein the dental abrasive material is a member selected from the group consisting of zirconium silicate (ZrSiO calcium pyrophosphate (Ca P O anhydrous calcium hydrogen phosphate (CaHPO calcium hydrogen phosphate dihydrate (CaHPO '2l-I O); insoluble sodium metaphosphate [(NaPOQ calcium carbonate (CaCO alumina (A1 0 talc [Mg Si O (Ol-l) and mixtures thereof.

9. A stimulator, as claimed in claim 7, wherein the dental abrasive material comprises zirconium silicate.

10. A stimulator, as claimed in claim 9, wherein the zirconium silicate comprises a mixture of relatively large and relatively small zirconium silicate particles, with the relatively large particles predominating on a weight basis.

11. A stimulator, as claimed in claim 10, wherein the relatively large zirconium silicate particles lie in the range of about 10-75 microns particle size and the relatively small particles lie in the range of up to about 10 microns particle size, the said mixture comprising at least 50 percent by weight of the relatively large particles.

12. A stimulator, as claimed in claim 11, wherein the relatively small particles are substantially all less than about 3 microns particle size.

13. A stimulator, as claimed in claim 12, wherein the said mixture comprises a 9:1 weight ratio of relatively large to relatively small zirconium silicate particles.

14. An interdental stimulator adapted for use in cleaning and polishing tooth surfaces without undue abrasion and further adapted to safely stimulate gingival tissue, the said stimulator comprising:

a unitary body molded of insoluble plastic material, the said unitary body being of generally elongated shape and having first and second working ends disposed at opposite ends thereof;

the first working end being generally triangular in cross-section and tapering substantially to a point;

the second working end taking the form of a thin,

flexible, flat-sided projecting member of substantially uniform thickness; and

the plastic material having incorporated throughout up to about 20 percent by weight of a mixture of relatively large and relatively small zirconium silicate particles, the relatively large particles predominating on a weight basis, the zirconium silicate particles being relatively permanently embedded in the plastic material.

15. A stimulator, as claimed in claim 14, wherein the relatively large zirconium silicate particles lie in the range of about 10-75 microns particle size and the relatively small particles lie in the range of up to about l0 microns particle size, the said mixture comprising at least 50 percent by weight of the relatively large particles.

16. A stimulator, as claimed in claim 15, wherein the relatively small particles are substantially all less than about 3 microns particle size.

17. A stimulator, as claimed in claim 16, wherein the said mixture comprises a 9:1 weight ratio of relatively large to relatively small zirconium silicate particles. 

2. A stimulator, as claimed in claim 1, wherein the cross-section of the first working end generally takes the form of an isosceles triangle.
 3. A stimulator, as claimed in claim 1, wherein the surfaces of the first working end are curved outwardly slightly.
 4. A stimulator, as claimed in claim 1, wherein a second working end is provided at the end of the unitary body opposite the first working end, the second working end taking the form of a thin, flexible, flat-sided projecting member of substantially uniform thickness.
 5. A stimulator, as claimed in claim 1, wherein the plastic is nylon.
 6. A stimulator, as claimed in claim 1, wherein the plastic material has incorporated therein a dental abrasive material.
 7. A stimulator, as claimed in claim 1, wherein the dental abrasive is present in the plastic material at a level of about 5-15 percent by weight.
 8. A stimulator, as claimed in claim 1, wherein the dental abrasive material is a member selected from the group consisting of zirconium silicate (ZrSiO4); calcium pyrophosphate (Ca2P2O7); anhydrous calcium hydrogen phosphate (CaHPO4); calcium hydrogen phosphate dihydrate (CaHPO4.2H2O); insoluble sodium metaphosphate ((NaPO3)x); calcium carbonate (CaCO3); alumina (Al2O3); talc (Mg3Si4O10(OH)2); and mixtures thereof.
 9. A stimulator, as claimed in claim 7, wherein the dental abrasive material comprises zirconium silicate.
 10. A stimulator, as claimed in claim 9, wherein the zirconium silicate comprises a mixture of relatively largE and relatively small zirconium silicate particles, with the relatively large particles predominating on a weight basis.
 11. A stimulator, as claimed in claim 10, wherein the relatively large zirconium silicate particles lie in the range of about 10-75 microns particle size and the relatively small particles lie in the range of up to about 10 microns particle size, the said mixture comprising at least 50 percent by weight of the relatively large particles.
 12. A stimulator, as claimed in claim 11, wherein the relatively small particles are substantially all less than about 3 microns particle size.
 13. A stimulator, as claimed in claim 12, wherein the said mixture comprises a 9:1 weight ratio of relatively large to relatively small zirconium silicate particles.
 14. An interdental stimulator adapted for use in cleaning and polishing tooth surfaces without undue abrasion and further adapted to safely stimulate gingival tissue, the said stimulator comprising: a unitary body molded of insoluble plastic material, the said unitary body being of generally elongated shape and having first and second working ends disposed at opposite ends thereof; the first working end being generally triangular in cross-section and tapering substantially to a point; the second working end taking the form of a thin, flexible, flat-sided projecting member of substantially uniform thickness; and the plastic material having incorporated throughout up to about 20 percent by weight of a mixture of relatively large and relatively small zirconium silicate particles, the relatively large particles predominating on a weight basis, the zirconium silicate particles being relatively permanently embedded in the plastic material.
 15. A stimulator, as claimed in claim 14, wherein the relatively large zirconium silicate particles lie in the range of about 10-75 microns particle size and the relatively small particles lie in the range of up to about 10 microns particle size, the said mixture comprising at least 50 percent by weight of the relatively large particles.
 16. A stimulator, as claimed in claim 15, wherein the relatively small particles are substantially all less than about 3 microns particle size.
 17. A stimulator, as claimed in claim 16, wherein the said mixture comprises a 9:1 weight ratio of relatively large to relatively small zirconium silicate particles. 